The present invention relates to a camera capable of emitting an information light from its photographic lens toward the object side to give information about photographing to one standing on the object side.
In taking a picture of a person with a common camera, it is impossible for the person standing on the object side as an object to be photographed to know whether or not he is correctly included within the area of the object field. Also, in taking a picture of himself with a camera mounted on a tripod using a self-timer, it is very difficult for him to ascertain whether the self-timer is correctly operating or not. Therefore, there has been a desire for a camera capable of giving such information about photographing to a person standing on the object side.
In conformity with such desire, some solutions to the problem have been developed recently. According to one of the known solutions, a half mirror is interposed in the optical path for a finder on the camera side. Through an optical path different from the finder optical path, a beam of light is introduced into the half mirror which directs the light beam in the direction opposite to that of the object image forming light. After travelling along the finder optical path in the opposite direction, the information light is emitted from the photographic lens toward the object side.
In another solution, a reticle one surface of which is formed as a light diffusion surface, is disposed in a finder optical path. The diffusion surface is illuminated by illumination light introduced into the reticle so as to produce a diffused light running along the finder optical path in the opposite direction. This diffused light is used as an information light. After being emitted through the photographic lens of the camera toward the object side, the diffused light forms an image of the reticle at a predetermined focal length and in a size approximately equal to the area of the picture field.
However, in those cameras capable of emitting phototaking information toward the object side, it is desirous for a photographer to have a bright view field and further, a bright and accurate information light. A bright view field is important especially for X.L cameras.
While said known solutions enable the camera to emit an information light toward the object side in a simple manner, they have some important disadvantages. For example, in case of the former construction, the half mirror interposed in the object image forming light causes a substantial reduction of the quantity of the image forming light and therefore the view field of the finder becomes dark. In the case of the latter construction, a portion of the diffused light from the light diffusing surface runs toward the eye piece along the finder optical path and has an adverse effect on the object image visible in the finder view field. Moreover, they have a common drawback that the intensity of the information light travelling toward the object side is relatively low as compared to that of illumination light from the light source and therefore it is difficult to obtain a bright and clear information light.
For a camera it is essential to keep the view field bright and easily visible to the operator of the camera. On the other hand, to the object side one, it is desirable that the information light be as bright as possible and the information light should indicate the area of the object field (picture field) as clearly as possible.